Actually, you can use it to check if someone try to access your PC.
As you see, Client is on the left (your IP address) and Server is on the right (your server).
The problem is when your IP is suddenly on the right (Server) and the other IP is on the left (Client).
Mean, that your PC is working as a server.

It’s normal when you log on to Chat program like Skype, Yahoo Messenger, etc. It’s point to point connection, so it’s OK.
Except that, you must be aware.